There are many known airflow control devices for regulating the flow of air from one area to another area. In regards to refrigerators in particular, known refrigerator arrangements utilize a compressor refrigeration system for chilling the environment within the freezer compartment of the refrigerator. The refrigerated food compartment of the refrigerator is cooled by moving cold air from the freezer compartment into the refrigerated compartment. An airflow damper is provided between the refrigerated compartment and the freezer compartment to regulate the amount of cold air that is allowed to pass from the freezer compartment to the refrigerated compartment.
It is known to provide some type of user input for regulating and controlling the operation of the airflow damper. In lower end refrigerators, the damper mechanism commonly is a simple slider type damper having a fixed opening and a slide thereover. The slide portion is connected to a knob via a rod or other link mechanism. Adjustment of the knob position moves the slider mechanism to adjust the effective size of the opening through the damper, to regulate, at least to some limited extent, the amount of cold air allowed to enter the refrigerated compartment from the freezer compartment. The slider remains in the selected position until moved again by readjustment of the knob position. While some minimal control results, the refrigerated compartment is not truly temperature controlled, and will become colder or warmer under various operating and use conditions of the refrigerator. For example, if the refrigerated compartment is opened frequently and the damper is positioned for substantially restricted flow, insufficient airflow from the freezer compartment will result in the refrigerated compartment becoming warm. Conversely, if the refrigerated compartment is opened only infrequently, the temperature therein may approach the temperature of the freezer compartment with a fixed opening damper as described. Advantages of this type of damper include simplicity and inexpensive cost. A disadvantage is the relative inaccuracy of the temperature control provided thereby.
In a somewhat more functional design, the damper is a mechanically operated device connected to a thermostat. Refrigerant in the damper mechanism provides operational control. As the temperature in the refrigerated compartment changes, the refrigerant will expand or contract. Thus, if the refrigerated compartment door is opened frequently, or left open for long periods of time such that the compartment warms, the refrigerant will expand, causing the damper to open. As the refrigerated compartment cools, the refrigerant contracts, in turn causing the damper to close. Thus, damper opening and closing is controlled in relation to the actual temperature in the refrigerated compartment. Disadvantages of systems of this type include the cost and complexity of the system, wider than desirable temperature swings in the refrigerated compartment, and the disadvantage of using a toxic fluid in the control system.
In general, more energy efficient refrigerators have electronically controlled refrigerated and freezer compartments. A micro-controller monitors the refrigerator use and compartment temperatures, and controls airflow between the compartments for precisely regulated temperature in the refrigerated compartment. An electrically actuated damper receives a signal from the micro-controller, determining when to open and close the damper. User input adjusts the relative temperature level to which the refrigerated compartment is controlled. Drawbacks to known systems of this type include the relative complexity of the system and the cost associated with it. The electrically actuated damper is typically a motor driven device consisting of a gearbox and capacitors. The motor and gearbox are relatively robust to withstand potential frost or freezing conditions in the damper unit. The motor has sufficient power along with the gearbox to break loose the moveable components, if frosting or freezing occurs. Nevertheless, severe frost over can cause the damper to malfunction and can result in damage. Systems of this type are undesirably large, reducing the space available for storing food.
What is needed in the art is a refrigerator damper capable of accurately regulating the refrigerated compartment temperature, yet which is simple, compact and inexpensive to manufacture. Additionally, new, inexpensive and reliable methods to control frost over of the damper are needed.